Crosslinkable composition cross-linkable by real michael addition reaction and resins for use in said composition

ABSTRACT

An RMA crosslinkable composition having at least one crosslinkable component including reactive components A and B each including at least 2 reactive groups, the at least 2 reactive groups of component A being acidic protons (C—H) in activated methylene or methine groups and the at least 2 reactive groups of component B are activated unsaturated groups (C═C) and a base catalyst (C) which reactive components A and B crosslink by Real Michael Addition (RMA) reaction under action of the base catalyst, characterised in that the at least one crosslinkable component including reactive components A and B in the composition have a total hydroxy number of less than 60, preferably less than 40 and more preferably less than 20 mg KOH/g solids. Further, specific resins A and B having a low hydroxy number for use in RMA cross-linkable compositions and a process for the manufacture thereof.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT application numberPCT/EP2012/069904 filed on 8 Oct. 2012, which claims priority fromEuropean application number 11184439.5 filed on 7 Oct. 2011. Bothapplications are hereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a crosslinkable compositioncross-linkable by real Michael addition (RMA) reaction and resins foruse in said composition. Real Michael Addition is a reaction wherein areactive component B with at least 2 activated unsaturated groups(hereafter also referred to as the RMA acceptor) and a reactivecomponent A with at least 2 acidic protons C—H in activated methylene ormethine groups (hereafter also referred to as the RMA donor) react inthe presence of a strong base catalyst.

2. Description of the Related Art

RMA chemistry can be tuned to give very fast curing compositions (alsoat lower curing temperatures) in coating compositions at acceptable orgood pot lives and good material properties, which makes this chemistryvery attractive as a basis for coating compositions. Details of RMAcross-linkable compositions using a latent based cross-linking catalystare described by inventors of the present application in WO2011/055463which is herewith incorporated by reference.

Real Michael addition is activated by strong bases. In tuning thereactivity of coating systems in view of achieving a desirable dryingprofile, there are various requirements to balance. The drying profile(also referred to as the reaction profile or as the curing profile) isthe progress of the cross-linking reaction as a function of time. It isrequired that the drying profile allows build-up of mechanicalproperties as fast as possible, to help the productivity of the coater.There is also a desire for crosslinkable compositions that can be simplycured in ambient conditions, as opposed to for example compositionscomprising photo-latent amine catalysts, known from T. Jung et al Farbeand Lacke October 2003.

On the other hand, it is required to have a good appearance of theresulting coating. This implies the need for sufficient levelling duringthe immediate period after application, when the curing coatingcomposition is present as a liquid and capable of such levelling. Thisalso implies the need for absence of artefacts like solvent inclusionsor gas inclusions or other surface irregularities that may occur ifcuring is very fast, especially if it is faster at the surface than indeeper layers, which is often the case if curing occurs at the timescale of solvent evaporation or surface activation of a catalyst. Also,film hardness build-up will be affected under conditions in whichsolvent entrapment occurs. The described requirements are to some extentopposing each other. For a fast curing profile high levels of catalystare preferred, whereas at the same time such high levels of catalystsmay negatively influence surface appearance and hardness development.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is to provide improved cross-linkablecompositions that provide optimum coating properties in the delicatebalance of these apparently counteracting requirements, in particular incrosslinkable compositions having a high solid content. In particular,there is a continuous desire to improve the appearance and hardness ofthe coatings and the problem is to provide RMA cross-linkablecompositions that result in coatings having improved appearance andhardness.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the conversion of the acryloyl (as followed by FTIRat 809 cm⁻¹) in the preferred acryloyl/malonate system using succinimidas component D.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following is a description of certain embodiments of the invention,given by way of example only and with reference to the FIGURE.

According to the invention there is provided an RMA crosslinkablecomposition comprising at least one crosslinkable component comprisingreactive components A and B, each comprising at least 2 reactive groupswherein the at least 2 reactive groups of component A are acidic protons(C—H) in activated methylene or methine groups and the at least 2reactive groups of component B are activated unsaturated groups (C═C)and a base catalyst (C) which reactive components A and B crosslink byReal Michael Addition (RMA) reaction under action of the base catalyst,characterised in that the at least one crosslinkable componentcomprising reactive components A and B in the composition have a totalhydroxy number of less than 60, preferably less than 40 and morepreferably less than 20 mg KOH/g solids. It was surprisingly found thatcross-linkable compositions comprising the special cross-linkablecomponents with very low hydroxy number show significantly improvedhardness and improved appearance as is exemplified in the examples.

In a preferred embodiment the crosslinkable composition the catalyst Cis a carbonate salt according to formula X+ROCO2−, wherein X+ is anon-acidic cation, preferably quaternary ammonium or phosphonium, and Ris hydrogen or a substituted or unsubstituted alkyl, aryl, or aralkylgroup. Details of this latent base catalyst are described inWO2011/055463, which is herewith incorporated by reference.

The reactive components A and B can be in the form of separate moleculesand each independently in the form of polymers, oligomers, dimers ormonomers. Therefore, a “cross-linkable component comprising the activecomponent A” is sometimes also referred to herein as component A.Reactive components A and B can be combined in a single molecule.Optionally, even catalyst C can be combined in a single molecule withreactive component A and/or B. It is preferred that the cross-linkablecomposition comprises an oligomeric or polymeric resin A comprisingreactive components A. The invention also relates to oligomeric orpolymeric resin A comprising reactive components A having a hydroxynumber of less than 60, preferably less than 40, more preferably lessthan 20 and optionally even less than 10 mg KOH/g solids.

The invention further relates to oligomeric or polymeric resin Bcomprising reactive components B and having a hydroxy number of lessthan 60, preferably less than 40 and more preferably less than 20 mgKOH/g solids. The invention further relates to the use of resin A orresin B or mixtures of resin A and B for the preparation of RMAcross-linkable compositions.

Component A

Suitable examples of components A containing activated methylene ormethine groups are well known in the art. Preferred are the oligomericand/or polymeric components such as, for example, polyesters,polyurethanes, polyacrylates, epoxy resins, polyamides and polyvinylresins containing reactive component A in the main chain, pendant orboth. Preferably, the polymer is a polyester, polyurethane orpolycarbonate.

The crosslinkable component comprising reactive components A preferablyis a polymer comprising one or more reactive components A having astructure according to formula 2:

wherein R is hydrogen or an alkyl, aralkyl or aryl substituent and Y andY′ are same or different substituent groups, preferably alkyl, aralkylor aryl (R*), alkoxy (—OR*) or a polymer backbone or wherein the—C(═O)—Y and/or —C(═O)—Y′ is replaced by CN or phenyl and which polymerhas a hydroxy number of less than 60, preferably less than 40 and morepreferably less than 20 mg KOH/g solids. In case R is hydrogen, the CH2is the activated methylene and in case R is not hydrogen, the C—H is theactivated methine.

Good results can be obtained when the activated C—H group containingcomponent A is malonate (in Y and Y′ are —OR* in Formula 1) oracetoacetate (Y is —OR* and Y′ is —R* in Formula 1). Preferably morethan 50, preferably 60, 70, 80, 90 or 95% of the reactive components Ain the crosslinkable component are malonate groups. Componentscontaining both malonate and acetoacetate groups in the same moleculeare also suitable. Additionally, physical mixtures of malonate andacetoacetate group-containing components are suitable. Thecross-linkable component comprising reactive component A preferably is apolymer comprising an average of 2 to 20, preferably 4 to 10 active C—Hfunctions per molecule.

In a most preferred embodiment of the crosslinkable composition,component A is a malonate containing compound. It is preferred that inthe crosslinkable composition the majority of the activated C—H groupsare from malonate, that is more than 50%, preferably more than 60%, morepreferably more than 70%, most preferably more than 80% of all activatedC—H groups in the crosslinkable composition are from malonate. Inanother embodiment, the crosslinking composition comprises a componentA, for example a polymer, wherein more than 50%, preferably more than70%, more preferably more than 80% and most preferably more than 90% ofthe activated C—H groups are from malonate and a separate component, forexample another polymer, oligomer or monomer, comprising activated C—Hgroups not from malonate, for example acetoacetate.

Especially preferred malonate group-containing components for use withthe present invention are the malonate group-containing oligomeric orpolymeric esters, ethers, urethanes and epoxy esters containing 1-50,more preferably 2-10, malonate groups per molecule. In practicepolyesters and polyurethanes are preferred. It is also preferred thatsuch malonate group-containing components have a number averagemolecular weight (Mn) in the range of from about 100 to about 5000, morepreferably, 250-2500, and an acid number of about 2 or less. Alsomonomalonates can be used as they have 2 reactive C—H per molecule.Monomeric malonates can, in addition, be used as reactive diluents.

The invention also relates to a polymeric or oligomeric resin A, for usein a RMA cross-linkable composition, comprising one or more reactivecomponents A having a structure according to formula 2:

wherein R is hydrogen or an alkyl, aralkyl or aryl substituent and Y andY′ are same or different substituent groups, preferably alkyl, aralkylor aryl (R*), alkoxy (—OR*) or a polymer backbone or wherein the—C(═O)—Y and/or —C(═O)—Y′ is replaced by CN or phenyl and whichpolymeric or oligomeric resin A has a hydroxy number of less than 60,preferably less than 40 and more preferably less than 20 mg KOH/gsolids. Preferably, the polymeric or oligomeric resin is a polyester,polyether, polyepoxy, polyurethane or polycarbonate, more preferably apolyether, polyester or polyurethane, comprising reactive components A,preferably malonate or acetoacetate and preferably in an amount that theresin comprises an average of 2 to 20, preferably 4 to 10 active C—Hfunctions per molecule. Preferably, more than 50, preferably 60, 70, 80,90 or 95% of the reactive components A in the crosslinkable componentare malonate groups. Malonate containing resin A is preferred over forexample acetoacetate containing resin A because it provides improved potlife and coating hardness.

The resin A typically has a number molecular weight between 100-20000gr/mol, preferably between 250 and 10000 and in view of the rheology ofthe coating composition and the mechanical properties of the obtainedcoating more preferably between 300 and 6000 gr/mol and preferably anequivalent weight per reactive component A of 100-2000 gr/mol. The resinacid number this preferably less than 4, preferably less than 3, 2 or 1mg KOH/gr because a high acid number would result in inactivation of atleast a part of the base catalyst.

Component B

Components B generally can be ethylenically unsaturated components inwhich the carbon-carbon double bond is activated by anelectron-withdrawing group, e.g. a carbonyl group in the alpha-position.Suitable components B are known in the art, for example acryloyl esters,acrylamides, alternatively polyesters based upon maleic, fumaric and/oritaconic acid (and maleic and itaconic anhydride and polyesters,polyurethanes, polyethers and/or alkyd resins containing pendantactivated unsaturated groups. Acrylates, fumarates and maleates arepreferred. Most preferably, the component B is an unsaturated acryloylfunctional component.

It is also especially preferred that the acid number of the activatedunsaturated group-containing components (as of any of other componentused in the composition) is sufficiently low to not substantially impairactivity of the catalyst, so preferably less than about 2, mostpreferably less than 1 mg KOH/g. As exemplified by the previouslyincorporated references, these and other activated unsaturatedgroup-containing components, and their methods of production, aregenerally known to those skilled in the art, and need no furtherexplanation here. Preferably the functionality is 2-20, the equivalentweight (EQW: average molecular weight per reactive functional group) is100-2000, and the number average molecular weight preferably is Mn200-5000.

The advantages of the invention are particularly manifest in criticallydifficult compositions comprising not only a high solids content butalso aimed at a high crosslinking density, with relative highconcentrations and functionalities of functional groups, for example incase the component A is a compound, in particular an oligomer orpolymer, comprising an average of 2 to 30, preferably 4 to 20 and morepreferably 4-10 activate C—H per polymer chain.

Typically, the concentrations of the functional groups in components Aand B, and their relative stoichiometry, are chosen such that good filmproperties following cure may be expected, with efficient use of thesefunctional groups. Typically, stoichiometries C—H/C═C are chosen o befrom 0.1 to 10, preferably 0.5 to 3, more preferably 0.7 to 3, mostpreferably 0.8/1.5.

The invention also relates to a polymeric or oligomeric resin B for usein a RMA cross-linkable composition comprising one or more reactivecomponents B comprising activated unsaturated groups (C═C), preferablyunsaturated acryloyl or maleate functional groups (preferably acryloyl)or an acrylamide and which polymeric or oligomeric resin has a hydroxynumber of less than 60, preferably less than 40 and more preferably lessthan 20 mg KOH/g solids. The resin B preferably is a polyester,polyether, polyepoxy, polyurethane or polycarbonate comprising reactivecomponent B and preferably has a number molecular weight between 300 and20000 gr/mol, preferably between 300 and 10000 or 6000 gr/mol. The priorart commonly uses TMPTA which has a molecular weight of 296. The resin Bpreferably has a equivalent weight per reactive component A or B of100-2000 gr/mol and an acid number less than 4, preferably less than 3,2 or 1 mg KOH/gr.

The invention also relates to a resin mixture of polymeric or oligomericresin A and polymeric or oligomeric resin B as described above for usein a RMA cross-linkable compositions and to the use use of resin A orresin B or of a resin mixture of resin A and resin B as cross-linkablecomponents in an RMA cross-linkable composition. Herein it is preferredthat at least one of resin A or resin B comprise at least 3 reactivecross-linking groups for forming a three-dimensional cross-linkednetwork and at least one of resin A or resin B comprises at least tworeactive cross-linking groups and wherein resin A or B or both have anaverage of 3-30 reactive cross-linking groups per polymer or oligomermolecule.

Process for the Preparation of the RMA Resins A and B According to theInvention.

The invention also relates to a process for the preparation of the RMAresins A and B according to the invention, in particular, to a processfor the preparation of resin A comprising transesterification of apolyol with reactive component A in the form of an carboxylic acid ester(Y and Y′ are alkoxy (—OR*)) and to a process for the preparation ofresin B comprising transesterification of a polyol with reactivecomponent B, preferably an acryloyl, in the form of carboxylic acidester or by direct esterification of a polyol with reactive component Bin the form of carboxylic acid.

What is particularly important is that in the preparation process ofresin A or resin B the relative amounts of the components in thereaction mixture and the reaction time in combination with the reactiontemperature are chosen such that the resulting resin A or B has therequired low hydroxy number of less than 60, preferably less than 40 andmore preferably less than 20 mg KOH/g solids. In reaction between apolyol and reactive component A, the hydroxy value will be high in thebeginning of the reaction and will gradually decrease as hydroxy groupsof the polyol react with reactive component A. The skilled person cancalculate the required amounts of components such that the resultingresin A on completion of the reaction has a very low hydroxy value andcan determine by known techniques, such as acid-base titration whetherthe resulting resin has reacted sufficiently long to reduce the hydroxyvalue to the required level to form resin A or B.

The polyester resin used in the present invention can be prepared bycopolymerisation of one or more polyols, one or more polyacids, and oneore more esters of malonic acid and/or etylacetoacetic acid. A preferredway of preparing the polyesters of present invention is to prepare in afirst step a hydroxylfunctional polyester, and in later steptransesterifying the polyester of the first step with esters of malonicor ethylacetoacetic acid and a volatile alcohol, prefeably ethanol ormethanol.

The hydroxyfunctional polyester can also be prepared by reacting ahydroxyl functional polyester polyol with chain extenders, preferablylactones such as caprolactone, valerolactone, and butyrolactone.Alternatively this hydroxypolyester can be prepared by reacting apolyester bearing both hydroxyl and acid groups with one or more mono orpolyfunctional epoxy compounds. Suitable mono or polyfunctional epoxycompounds are mono-, di- or polyglycidyl ethers of (cyclo)aliphatic oraromatic hydroxyl compounds such as allyl alcohol, butanol,cyclohexanol, phenol, butyl phenol, decanol, ethylene glycol, glycerol,cyclohexane diol, mononuclear di- or trifunctional phenols, bisphenolssuch as Bisphenol-A or Bisphenol-F, and multinuclear phenols.

The polyols of the first step can also be prepared by reacting a hydroxyfunctional polyester of the first step with a mono- or polyfunctionalisocyanate compound. As suitable at least trifunctional isocyanates maybe mentioned a wide variety of monomeric and oligomeric polyfunctionalisocyanates. The polycarboxylic acids for the preparation of thepolyester polyol are preferably selected from the group of acyclic orcyclic polycarboxylic acids, the esters or the anhydrides thereof.Cyclic polycarboxylic acids include aromatic polycarboxylic acids andcycloaliphatic polycarboxylic acids. Included in this polycarboxylicacids are fatty acids, their esters, dimers and higher oligomers andmixtures thereof. Also included are the esters or the anhydrides thereofsuch as dimethyl ester and diethyl ester of malonic acid, succinicanhydride, octenyl succinic anhydride (any isomer or mixture of isomersof 4-octenyl-5-hydro-1,3furandione), dodecenyl succinic anhydride (anyisomer or mixture of isomers of 4-dodecenyl-5-hydro-1,3-furandione), andmixtures thereof.

The optionally co-condensed monocarboxylic acids may be aliphatic,cycloaliphatic, aromatic or mixtures thereof. Preferably, themonocarboxylic acid contains 6 to 18 carbon atoms, most preferably 7 to14 carbon atoms, such as octanoic acid, 2-ethylhexanoic acid,isononanoic acid, decanoic acid, dodecanoic acid, benzoic acid,hexahydrobenzoic acid, and mixtures thereof. Preferably, the polyol is acycloaliphatic or aliphatic polyol having 2 to 15 carbon atoms. Alsopreferred are mixtures of at least one polyol selected from trimethylolethane, trimethylol propane, glycerol, pentaerythritol, andditrimethylol propane with at least one diol having 2 to 15 carbonatoms. Preferred diols include 1,2ethane diol, 1,2-propane diol,1,3-propane diol, 3-methyl-1,3-propane diol, 2butyl-2-ethyl-1,3-propanediol, dimethylol propionic acid, and 1,4-cyclohexane dimethanol.Examples of suitable monofunctional alcohols include alcohols with 6-18carbon atoms such as 2-ethyl hexanol, dodecanol, cyclohexanol andtrimethyl cyclohexanol. The optionally co-condensed monocarboxylic acidsmay be aliphatic, cycloaliphatic, aromatic or mixtures thereof.Preferably, the monocarboxylic acid contains 6 to 18 carbon atoms, mostpreferably 7 to 14 carbon atoms, such as octanoic acid, 2-ethylhexanoicacid, isononanoic acid, decanoic acid, dodecanoic acid, benzoic acid,hexahydrobenzoic acid, and mixtures thereof. Typical hydroxy acids thatcan be used include dimethylol propionic acid, hydroxypivalic acid, andhydroxystearic acid. Suitable monofunctional epoxy compounds include theglycidyl esters of branched Monocarboxylic acids such as Cardura(R) Efrom Resolution. Polyurethane, polyether polyols can be prepared in theknown manner using suitable monomers as described above.

Preferably, in view of the desired mechanical and appearance propertiesof a coating prepared from the cross-linkable composition, the oligomeror polymer constituents of resin A are chosen such that the glasstransition temperature of the resin A is between −25 and +25° C., morepreferably between −20 and +20° C. and most preferably between −20 and+15° C. In combination with said resin A the glass transitiontemperature of resin B can be chosen between wider ranges, preferablybetween −50 and +25° C. The resins can be aliphatic or a mix ofaliphatic and aromatic constituents with an aromatic constituentspercentage chosen in view of the envisaged application. The amount ofaromatic compounds in resin A and in resin B and also in a mixture ofresin A and Resin B is preferably at most 60 wt % (relative to the totalweight of the resin or resin mixture), preferably at most 40, 20 or 10wt %. Good results were obtained in a preferred embodiment wherein resinA and resin B are aliphatic resins, i.e. comprising substantially noaromatic constituents (at most 5 wt %). In view of the RMA cross-linkingthe activity, the acid number of resin A and B is preferably less than 1mg KOH/g solids. In view of the properties of the resulting coating andthe reaction kinetics, the molecular weight is preferably low between300 and 6000 gr/mol. In view of achieving a good drying and coatinghardness, the hydroxy number is preferably as low as possible; mostpreferably less than 20 and optionally even less than 10 mg KOH/gsolids. Even though the molecular weight is relatively low, in view ofthe mechanical properties of the resulting coating, the Resins must havesufficient cross-linking functionality. Preferably, resin A and resin Bhave an average functionality of 3-30 reactive cross-linking groups perpolymer or oligomer molecule. For resin A the functionality ispreferably between 5 and 30, more preferably between 10 and 30. Suitablecombinations can be a mixture of resin A with relatively highfunctionality and resin B with a relatively low functionality, inparticular resin A with functionality between 10 and 30 and resin B witha functionality of 3-20 or 3-10.

Component C

The base catalyst C can in principle be any known catalyst suitable forcatalyzing RMA reactions. Preferably, in view of achieving good pot-lifein combination with low temperature curing, the cross-linkingcomposition comprises a catalyst system C comprising a strong basedblocked by a volatile acid which is activated by evaporation of thisacid. A suitable catalyst system C comprises a strong base blocked by acarbon dioxide, or the blocked catalytic species are of formula ROCO2−,R being a optionally substituted alkyl, preferably C1-C4 radical orhydrogen, preferably the catalyst comprises a blocked base anion and anon-acidic cation, preferably a quaternary ammonium or phosphoniumcation. Suitable catalyst C is described in WO2011/055463 herewithincorporated by reference. It is preferred that the crosslinkingcatalyst is utilized in an amount ranging between 0.001 and 0.3 meq/gsolids, preferably between 0.01 and 0.2 meq/g solids, more preferablybetween 0.02 and 0.1 meq/g solids (meq/g solids defined as mmoles baserelative to the total dry weight of the crosslinkable composition, notcounting particulate fillers or pigments). Alternatively, the catalystsystem C is activated by reaction of an epoxy component with a tertiaryamine, or an anion.

For the CO2 deblocking catalyst systems, it was surprisingly found thatsignificantly better potlife could be achieved in a composition whereincomponent A is a malonate, which composition further comprises 0.1-10 wt%, preferably 0.1-5, more preferably 0.2-3 and most preferably 0.5-2 wt% water (relative to total weight of the coating composition).Preferably, the amount of water is chosen in an effective amount toincrease gel time with at least 15 minutes, preferably at least 30 min,more preferably at least 1 h, even more preferably at least 5 h, andmost preferably at least 24 h, 48 h. or at least 10%, 50% or 100%compared to the same composition without water.

Component D

The cross-linkable composition may comprise as an additive to improveappearance and or hardness of the coating an X—H group containingcomponent (D) that is also a Michael addition donor reactable withcomponent B under the action of catalyst C, wherein X is C, N, P, O orS, preferably C, N or P, preferably present in quantities of at least 50mole % relative to base generated by component C, and less than 30 mole% of C—H active groups from component A.

Component D as described in an catalysed RMA crosslinkablecompositioncan create a reactivity profile comprising an initialinduction time of lowered reaction rate directly after application andactivation of the system, followed by a relative increase of reactivityin later stages. This induction time can be tuned, to allow a “opentime” the period allowing flow and solvent and entrapped air bubbles toescape. The induction time allows a significantly higher amount of flowand levelling of the system, avoiding surface defects that may resultfrom very fast cure without these additives, and better hardnessbuild-up due to reduced solvent entrapment, while still benefiting fromthe full potential of the catalysts beyond this induction time, thuscreating an acceleration of the reaction at later stages to completecrosslinking at higher rate than would be found if simply using lowercatalyst levels. Also the high sensitivity of lower catalyst levelstowards accidentally present acid contaminations is avoided.

Although the advantages of the invention are apparent in layers ofnormal thickness, the crosslinkable composition according to theinvention is particularly suitable for making thick layers. Thick layersare considered to be layers having a cured dry thickness of at least 50or more than 70 micrometers. In thick layer applications the risk of airand solvent inclusions is higher. This is particularly pronounced in RMAcrosslinkable compositions that are cured at low temperature in therange from 10 to 60° C. where resins are more viscous and levelling isdifficult.

The X—H group in component D has a higher acidity than the C—H groups incomponent A, preferably being characterized in that component D has apKa (defined in aqueous environment) of at least one unit, preferablytwo units, less than that of component A. Preferably the pKa of the X—Hgroup in component D is lower than 13, preferable lower than 12, morepreferably lower than 11 most preferably lower than 10. An excessiveacidity may create problems with components in the catalyst system;therefore hence the pKa is preferably higher than 7, more preferablyhigher than 7.5 and optionally higher than 8. The acidity differenceassures that on application of the coating, component D is activated(deprotonated) preferentially over component A.

Preferably component D is selected from one or more compounds from thegroup of Compounds D1 comprising C—H acidic protons (X is C) inactivated methylene or methine groups and Compounds D2 comprising N—Hacidic compound (X is N). Suitable components D2 are an aza-acidiccompounds (X is N) preferably comprising a molecule containing the N—Has part of a group Ar—NH—(C═O)—, —(C═O)—NH—(C═O)—, or of a group—NH—(O═S═O)— or a heterocycle in which the nitrogen of the N—H group iscontained in a heterocyclic ring, more preferably component D2 is animide derivative, preferably an (optionally substituted) succinimide orglutarimide. Other suitable components D2 are hydantoin derivatives, forexample 5,5-dimethylhydrantoin, sulfonamides, for example aromaticsulfonamides as benzene- or toluenesulfonamide or heterocycliccompounds, for example triazoles or a pyrazoles, or a uracil derivative.

In the crosslinkable composition, the X—H groups in component D arepresent in an amount corresponding to at least 50 mole %, preferable atleast 100 mole %, most preferably at least 150 mole % relative to theamount of base to be generated by catalyst C. The appropriate amount isvery much determined by the acid base characteristics of component Drelative to component A, and the reactivity of the corresponding anionsrelative to B, so may vary for different systems. It is noted that theopen time improving effect can in some cases be obtained at very smallamounts of component D, which is very advantageous because such smallamounts do not or not significantly affect the properties of theresulting cured composition; for example the chemical and mechanicalproperties of a coating. Typically the X—H groups in component D arepresent in an amount corresponding to no more than 30 mole %, preferablyno more than 20, optionally no more than 10 mole % relative to C—H donorgroups from component A. Preferably, the X—H functionality (number ofgroups per molecule) of component D is low, preferably less than 4, morepreferably less than 2, most preferably it is 1.

The crosslinkable composition may comprise next to one or more differentcomponents D a component D1 comprising acidic protons (C—H) in activatedmethylene or methine groups having a higher acidity than component A andwhich are also is reactive towards component B, Such component D1 canalso contribute to the open time improving effect, however in order tohave a significant effect D1 should be typically be present in an amountbetween 10-40 mol % (relative to total RMA C—H), which is asignificantly higher amount than for component D.

The difference in acidity of the two C—H acidic components A and D1 ischosen preferably in that wherein the pKa of component D1 is between 0.5and 6, preferably between 1 and 5 and more preferably between 1.5 and 4units lower than the pKa of component A. Preferably, component A is amalonate containing component and component D1 is an acetoacetate oracetylacetone containing component, preferably of low C—H functionality(preferably less than 10, more preferably less than 5, most preferablyit is no more than 2. Suitable components D and A2 are listed below withthe pKa value.

succinimide 9.5 ethosuximide 9.3 5,5-dimethylhydantoin 10.21,2,4-triazole 10.2 1,2,3-triazole 9.4 benzotriazole 8.2benzenesulfonamide 10.1 nitromethane 10.2 isatine 10.3 uracil 9.94-nitro-2-methylimidazole 9.6 phenol 10.0 ethylacetoacetate 10.7acetylacetone 9.0 diethylmalonate 13.0

The invention also relates to the use of the component D as describedabove as an additive to RMA cross-linkable compositions. The advantagesof improved appearance and improved hardness can be obtainedirrespective of the thickness of the layer but are particularly apparentin thick coating layers having a dry thickness of at least 50,preferably at least 60, 75, 100 and more preferably at least 125micrometer, for the improvement of the open time of the crosslinkablecomposition and for the improvement of the appearance and hardness ofthe resulting cured composition, in particular a coating.

In the crosslinkable composition the nature and amount of component D ischosen to yield, under the application and curing conditions chosen, anincrease in time to get to a 30% conversion level, of at least 3,preferably 5, more preferably 10 minutes, preferably less than 60, morepreferably less than 30 minutes, when compared to the same compositionwithout component D.

Solvent Component

The cross-linkable composition can be used without having any additionalsolvent. This would typically be the case when the cross-linkablecomponents in the composition have sufficient low viscosity and allcomponents together form a solution. A solvent may be added for exampleto reduce the viscosity in case of high solids content of relativelyhigh viscosity components, to mediate the reaction kinetics or in casethe composition contains certain additives that would require thesolvent. The solvent can be water or can be an organic solvent ormixtures thereof. Most preferred is to use an organic solvent. Theorganic solvent may contain (substantially) no water. However, it issometimes preferred in view of increasing pot life to add in addition toorganic solvent also a relatively small amount of water, preferablybetween 0.1 and 10 wt % (relative to the total weight of thecross-linkable composition).

For CO2 deblocking catalyst systems, the inventors further found thatadvantages can be achieved in pot life if in the crosslinkablecomposition at least part of the solvent is a primary alcohol solvent.The solvent can be a mixture of a non-alcoholic solvent and an alcoholsolvent. Preferably, the alcohol is present in an amount of at least 1,preferably 2, more preferably 3, most preferably at least 5, even morepreferably at least 10 wt % relative to the total weight of thecrosslinkable composition and in view of VOC constraints preferably atmost 45, preferably at most 40 wt %, most preferably less than 30 wt %.

The alcohol solvent preferably is one or more primary alcohols, morepreferably a mono-alcohol having 1 to 20, preferably 1-10, morepreferably 1-6 carbon atoms, preferably selected from the group ofethanol, n-propanol, n-butanol, n-amyl alcohol and butylglycol

In summary, the crosslinkable composition according to the inventioncomprises

-   -   a. between 5 and 95 wt % of a resin A having reactive components        A comprising at least 2 acidic protons C—H in activated        methylene or methine, said resin A having a hydroxy number of        less than 60, preferably less than 40 and more preferably less        than 20 mg KOH/g solids, and    -   b. between 5 and 95 wt % of a resin B having reactive components        B with at least 2 activated unsaturated groups (wt % relative to        the total weight of the crosslinkable composition) said resin B        having a hydroxy number of less than 60, preferably less than 40        and more preferably less than 20 mg KOH/g solids and    -   c. a catalyst system C that contains, or is able to generate a        basic catalyst capable of activating the RMA reaction between        components A and B, preferably at levels of 0.0001 and 0.5 meq/g        solid components,    -   d. optionally an X—H group containing component (D) that is also        a Michael addition donor reactable with component B under the        action of catalyst C, wherein X is C, N, P, O or S, preferably        C, N or P, preferably present in quantities of at least 50 mole        % relative to base generated by component C, and less than 30        mole % of C—H active groups from component A,    -   e. optionally between 0.1 and 80 wt % of solvent, preferably an        organic solvent which preferably contains at least 1 wt % of a        primary alcohol and optionally at least 0.1-10 wt % water    -   wherein the sum of the above-mentioned components is 100 weight        percent and wherein the resins A and B in the composition have a        total hydroxy number of less than 60, preferably less than 40        and more preferably less than 20 mg KOH/g solids.

Considering that the crosslinkable composition is a 2K composition whichis only formed shortly before the actual use, the invention also relatesto a kit of parts for the manufacture of the composition according tothe invention comprising a part 1 comprising components A and B but notC and part 2 comprising component C. A kit of parts for the manufactureof the composition according to the invention comprises a part 1comprising the cross-linkable components comprising reactive componentsA and/or B but no C and part 2 comprising component C

The invention also relates to the use of the crosslinking compositionaccording to the invention in a method for the manufacture of coatingcompositions, films or inks and to coating compositions, inks or filmscomprising the crosslinking composition according to the invention andfurther application oriented additives for example one or more coatingadditives like pigments, co-binder, solvents etc.

The invention also relates to a process for making a coating layerhaving a fully cured dry thickness of at least 70, 75, 80 or 100 andmore preferably at least 125 micrometer and having a good surfaceappearance and hardness of the resulting cured composition comprisingmixing the components A, B with cayalyst C shortly before use to form acoating composition according to the invention, applying a layer of thecoating composition on a substrate and allowing the curing thereof attemperature between 0 and 60° C.

The foregoing more general discussion of the present invention will befurther illustrated by the following specific examples, which areexemplary only.

Molecular weights were measured by GPC in THF, and expressed inpolystyrene equivalent weights.

Persoz hardness measurement: Persoz pendulum hardness was measured in aclimatized room at 23° C., and 55+/−5% relative humidity. Hardness ismeasured with a pendulum acc. Persoz as described in ASTM D 4366.

Drying time was determined by firmly pressing the thumb in the paintfilm. The time was recorded when there was no visible trace left in thepaint film.

Resin Example According to the Invention Preparation of MalonatePolyester Resin I

Into a reactor provided with a distilling column filed with Raschigrings were brought 4.691 moles of neopentyl glycol, 2.173 moles ofhexahydrophthalic anhydride and 0.0012 moles of butyl stannoic acid. Themixture was polymerised at 240° C. under nitrogen to an acid number of0.2 mg KOH/g. The mixture was cooled down to 130° C. and 2.819 moles ofdiethylmalonate were added. The reaction mixture was heated to 170° C.and ethanol was removed under reduced pressure. The nearly colourlessmaterial was cooled down and diluted with 178 g of butyl acetate to a85% solid content. The final resin had an acid number of 0.3 mg KOH/gsolids, an OH value of 8 mg KOH/g solids. The resin was diluted to 85%solids with butyl acetate.

Resin Example According to the Invention Preparation of MalonatePolyester Resin II

In a similar way as under (I) were brought 4.521 moles of neopentylglycol, 2.095 moles of hexahydrophthalic anhydride, 0.232 moles of Butylethyl propane diol and 0.0011 moles of butyl stannoic acid were broughtin a reactor. The mixture was polymerised at 240° C. under nitrogen toan acid number of 0.2 mg KOH/g. The mixture was cooled down to 130° C.and 2.717 moles of diethylmalonate were added. The reaction mixture washeated to 170° C. and ethanol was removed under reduced pressure. Thenearly colourless material was cooled down and diluted with 178 g ofbutyl acetate to a 85% solid content. The final resin had an acid numberof 0.3 mg KOH/g solids, an OH value of about 30 mg KOH/g solids. Theresin was diluted to 85% solids with butyl acetate.

Comparative Resin Example Preparation of Comparative Malonate PolyesterResin III

In a similar way as under (I) were brought 4.341 moles of neopentylglycol, 2.011 moles of hexahydrophthalic anhydride, 0.464 moles of Butylethyl propane diol and 0.0011 moles of butyl stannoic acid were broughtin a reactor. The mixture was polymerised at 240° C. under nitrogen toan acid number of 0.2 mg KOH/g. The mixture was cooled down to 130° C.and 2.609 moles of diethylmalonate were added. The reaction mixture washeated to 170° C. and ethanol was removed under reduced pressure. Thenearly colourless material was cooled down and diluted with 178 g ofbutyl acetate to a 85% solid content. The final resin had an acid numberof 0.3 mg KOH/g solids, an OH value of about 60 mg KOH/g solids. Theresin was diluted to 85% solids with butyl acetate.

Preparation of Paint

Paints were prepared according the composition in the table. The pigmentwas dispersed in the mixture of Disperbyk and Sartomer (which iscross-linkable component B: DiTMPTA isdi-trimethylolpropane-tetraacrylate) with a high shear stirrer for 15minutes. Then the other ingredients were added under stirring. Prior toapplication the catalyst solution was added.

Preparation of the Catalyst Solution

A catalyst solution was formed as follows: to 8.03 g of a 55% solutionof tetra-butylammoniumhydroxide were added 11.05 g of diethylcarbonateand 6.74 g of isopropanol.

Sartomer SR355 17.77 17.59 17.41 Disperbyk 163 1.11 1.10 1.09 Kronos2310 37.27 36.91 36.53 Example Resin I 29.95 Example Resin II 29.66Comparative Resin III 29.36 OHV (mg KOH/g) 8 30 60 Sartomer SR355 1.711.69 1.67 Ethyl acetoacetate 1.66 1.64 1.63 Byk 310/315 [1:4] 0.28 0.280.27 Succinimide 0.44 0.43 0.43 Benzotriazole 0.00 0.00 0.00 Methylethyl ketone 3.35 3.32 3.29 Butyl acetate 1.17 1.16 1.15 Propanol 0.560.55 0.55 Thinner 4.66 4.61 4.57 Catalyst solution 2.51 2.48 2.46 Total100.00 100.00 100.00 Hardness Persoz (after 3 118 88 19 days) Dryingtime 1 h 10 +4 hrs +24 hrs

The examples above show that the hardness of the coating compositionstrongly depends on the hydroxy value of the resin. A hydroxy value of60 or more will lead to an unacceptable long drying time and a very slowhardness built.

PRIOR ART Comparative Resin Example

WO 2011/055463, describes in Example 4 Formulations made from a malonatepolyester component A-1 and TMPA as the cross-linkable component B-1 andvarious catalysts. The malonate polyester A-1 had an OH value of 83.2 mgKOH/g. Apart from the hydroxy value, the malonate polyester A-1 issimilar to the above described malonate polyester I and II. The catalystC-5 (tetrabutylammonium ethylcarbonate) that has been used is thecatalyst used in the above paint formulations. The Perzos hardness was65 after 1 month curing time, whereas the resin according to theinvention having a low hydroxy value as a significantly higher hardness(88) already after three days curing time.

The invention will be further illustrated by the following specificexamples, which are exemplary only.

Molecular weights were measured by GPC in THF, and expressed inpolystyrene equivalent weights. Viscosities were measured with a TAInstruments AR2000Rheometer, using a cone and plate setup (cone 4 cm 1°)at 1 Pa stress.

Tube and ball method for pot life determination: A flat bottomed testtube (internal diameter 15 mm, length 12.5 cm), carrying two marks, 5 cmapart is filled with 20 ml of paint. A steel ball with a diameter of 8mm is added, and the tube is closed with a snap cap. The tube is heldunder an angle of 10° and the steel ball is allowed to roll on the wallof the test tube. The time needed to roll between the two marks is takenas a measure for the viscosity. The time needed to double in viscosityis taken as the pot life. If necessary this time is calculated by linearinterpolation between two measurements. This method was used for thepigmented formulations. For the clear formulations, a glass test tube(length 12 cm, diameter 13 mm) was filled with a stainless steel ball of12 mm diameter, and the formulation to be studied to leave a verylimited head space, and closed. Time was recorded for the ball to falland pass a distance of 5 cm when the tube was tilted vertically. Anaverage was taken over 2 measurements.

Drying recorder drying time: For determining the recorder drying time,paint was applied on a glass panel with a doctor blade with a 90μ gap.The drying time was measured with a Gardco electronic drying timerecorder, type DT-5020, set on a cycle time of 60 minutes. Drying timewas recorded as the time were the stylus left no more visible trace onthe film.

TNO cotton ball drying times: Dust-dry and tack-free times were measuredaccording to the so-called TNO method with a wad of cotton-wool.Dust-dry time means the time needed for the coating after dropping thewad on the surface of the coating and after leaving it there for 10seconds, to get no residue of the wool-cotton sticking onto the surfaceafter blowing away the wad. For tack-free time the same holds but now aweight load of 1 kg is applied on the wad for 10 seconds.

Persoz hardness measurement: Persoz pendulum hardness was measured in aclimatized room at 23° C., and 55+/−5% relative humidity. Hardness ismeasured with a pendulum acc. Persoz as described in ASTM D 4366. Forthe gradient layer thickness panels, hardness is measured at differentspots and corresponding layer thickness is measured. If necessary thehardness at a certain layer thickness is calculated by linearinterpolation of the measurement at two different layer thicknesses.Layer thicknesses were measured with a Fischer Permascope MP40E-S.

Optical evaluation spayed pigmented paints: Paint was sprayed with adevilbiss spraygun, nozzle FF-1.4 with an air pressure of 3.5 bar. Thepaint was prayed in a continuous layer over the entire surface of a55×10 cm steel panel. A consecutive layer was sprayed starting 10 cmfrom the right edge. Several layers were built up, moving to the rightso that a layer thickness gradient was build up from the left to right.Films were allowed to dry horizontally at 23° C., 45% RH. Layerthicknesses were measured with a Fischer Permascope MP40E-S. At 100μlayer thickness, a picture was taken with an Olympus SZX10 microscope(1× magn) equipped with a digital camera.

Wavescan analysis: The panels as described above were analyzed using theWavescan II of Byk instruments. Data were stored using Autochartsoftware from Byk. Analysis was done in the direction perpendicular tothe thickness gradient. In this instrument the light of small laserdiode is reflected by the surface of the sample under an angle of 60°,and the reflected light is detected at the gloss angle (60° opposite).During the measurement, the “wave-scan” is moved across the samplesurface over a scan length of approx. 10 cm, with a data point beingrecorded every 0.027 mm. The surface structure of the sample modulatesthe light of the laser diode. The signal is divided into 5 wavelengthranges in the range of 0.1-30 mm and processed by mathematicalfiltering. For each of the 5 ranges a characteristic value (Wa 0.1-0.3mm, Wb 0.3-1.0 mm, We 1.0-3.0 mm, Wd 3.0-10 mm, We 10-30 mm) as well asthe typical wave-scan-values longwave (LW, approx. 1-10 mm) andshortwave (SW, approx. 0.3-1 mm) is calculated. Low values mean a smoothsurface structure. Additionally a LED light source is installed in thewave-scan DOI and illuminates the surface under 20 degrees after passingan aperture. The scattered light is detected and a so-called dullnessvalue (du, <0.1 mm) is measured. By using the three values of the shortwave range Wa, Wb and du a DOI value is calculated. (see Osterhold e.a.,Progress in Organic Coatings, 2009, vol. 65, no4, pp. 440-443).

The following abbreviations were used for chemicals used in theexperiments: DiTMPTA is di-trimethylolpropane-tetraacrylate (obtainedfrom Aldrich (MW=466 g/mol)) or used as Sartomer SR355 (suppliedcommercially by Sartomer); Disperbyk 163 is a dispersant commerciallysupplied by Byk; Byk 310 and 315 are additives commercially supplied byByK; Kronos 2310 is a TiO2 pigment commercially supplied by Kronos, TBAHis tetrabutylammonium hydroxide, BuAc is Butyl acetate, MEK is Methylethyl ketone (2-Butanone); EtAcAc is ethyl acetoacetate; DEC is diethylcarbonate; IPA is isopropanol; RT is room temperature.

Preparation of Malonate Polyester A According to the Invention

Into a reactor provided with a distilling column filed with Raschigrings were brought 17.31 mol of neopentyl glycol, 8.03 mol ofhexahydrophthalic anhydride and 0.0047 mol of butyl stannoic acid. Themixture was polymerised at 240° C. under nitrogen to an acid number of0.2 mg KOH/g. The mixture was cooled down to 130° C. and 10.44 mol ofdiethylmalonate was added. The reaction mixture was heated to 170° C.and ethanol was removed under reduced pressure. The nearly colourlessmaterial was cooled down and diluted with 420 g of butyl acetate to a90% solid content. The final resin had an acid number of 0.3 mg KOH/gsolids, an OH value of 20 mg KOH/g solids and a weight average molecularweight of 3400 Da.

Catalyst Solution C1

Catalyst solution was prepared by reacting 59.4 g a TBAH solution (40%in water) with 13.5 g DEC (reacting overnight at RT), with 14.5 gisopropanol as co-solvent, following the corresponding ethocarbonatespecies development. Titration indicated that blocking was complete, andthat the concentration of blocked base was 0.83 meq/g solution.

Catalyst Solution C2

To 43.6 g of a 45% aqueous solution of TBAH were added 36.6 g ofisopropanol and 60 g of DEC. After standing overnight the mixture wasfiltered over paper. Titration showed that the catalyst contained 0.52meq of blocked base per gram solution.

No-D Example Formulation 1, Example Formulations 1-4

Formulations were prepared based on a malonate donor resin A, DiTMPTA asacryloyl donor resin, and the indicated amount of succinimide, andthinned to a viscosity of 160 mPas with a mixture of MEK/BuAc 1:1 byvolume. This was mixed with an amount of catalyst solution C1. Listed intable A are the details of the overall composition. Catalyst amounts are50 meq/g solids, water levels are 1.8 wt %, isopropanol at 0.7 wt %,ethanol level estimated at 0.2 wt %.

TABLE A Code No-D1 Ex1 Ex2 Ex3 Ex4 malonate ester A/g 15.0 15.0 15.015.0 15.0 di-TMPTA/g 6.6 6.6 6.6 6.6 6.6 succinimide/mg 0 149 174 199298 mole % succinimide on cat 0 150 175 200 300 MEK/BuAc (1:1)/g 4.5 4.54.5 4.5 4.5 catalyst C1/g 1.2 1.2 1.2 1.2 1.2

Of these formulations, the drying behaviour at room temperature forfilms leading to a dry film thickness of around 70-75 mu was followedwith TNO cotton ball drying tests, and Persoz pendulum hardnessdevelopment was determined; also these results are listed in Table B.

TABLE B Code No-D1 Ex1 Ex2 Ex3 Ex4 mole % succinimide on cat 0 150 175200 300 TNO-drying dust-dry (min) 10′ 25′ 25′ 30′ 65′ tack-free (min)10′ 30′ 30′ 35′ 70′ Persoz hardness (sec) after time at RT: 4 h 31 107132 1 night 42 126 152 1 week 66 131 137 146 231

It can be seen that whereas No-D example 1 shows an extremely fastdrying, the actual Persoz hardness levels are low presumably due tosolvent entrapment in the system. Moreover, the appearance of this No-Dexample 1 is poor. Upon addition of low levels of succinimide (slightlyhigher than the levels of catalyst used), some retardation of the dryingis seen, but still giving drying times considered as fast; however, itcan also be observed that the Persoz hardness development is stronglyimproved. Simultaneously, the example films with succinimide exhibit abetter appearance than No-D example 1.

Example formulations 5-7, and No-D example formulations 2-3 wereprepared as pigmented paints, having compositions as tabulated in TableC (amounts in grams).

TABLE C Code Ex5 Ex6 Ex7 No-D2 No-D3 Sartomer SR355 38.19 38.19 38.1938.19 39.19 Disperbyk 163 2.39 2.39 2.39 2.39 2.39 Kronos 2310 80.1280.12 80.12 80.12 80.12 malonate polyester A 58.70 67.69 67.69 58.7067.69 Sartomer SR 355 4.22 1.15 1.15 4.22 4.22 EtAcAc 4.81 0.00 0.004.81 0.00 Byk 310/315 [1:4 by mass] 0.60 0.60 0.60 0.60 0.60 Succinimide0.79 0.79 1.58 0.00 0.00 BuAc 2.52 2.52 2.52 2.52 2.52 MEK 7.20 7.207.20 7.20 7.20 catalyst solution C2 9.34 9.34 9.34 9.34 9.34 recorderdrying time (min) 14 15 44 4.3 8 potlife (min) 39 35 37 17 29 Persozhardness (sec) after 147 147 145 85 66 24 h (50 mu dry film)

Pot life of these pigmented paints were measured, and drying times ofthese paints drawn onto glass panels were determined with a dryingrecorder. These paints were also applied by spraying onto a steel panelto obtain gradient film thickness panel. Persoz hardness at 50 mu dryfilm thickness was determined after 24 hr RT cure; microscope pictureswere taken of the resulting coatings on these panels at approximately100 mu dry film thickness. Also, pot life of these paints were measured.Results are included in table C.

It can be observed from a comparison of No-D example 3 with examples 6and 7, that the addition of succinimide to the formulation gives clearadvantages in Persoz hardness build-up, and some advantage in pot life.Example 7, with a higher level of succinimide, shows a significantincrease in drying time, the 44 minute value can however still beconsidered as an acceptable to good value. Appearance of panels fromexamples 6 and 7 is much better than that of panels from No-D example 3,as can be judged from comparing the microscope photographs, No-D example3 showing many more defects.

Similar conclusions can be drawn from a comparison of No-D example 2,with example 5, now based on a formulation with acetoacetate includedbesides malonate as RMA donor groups. Example 5 (with succinimide added)exhibits higher Persoz hardness, a better pot life, and a betterappearance than No-D example 2 (not containing succinimide).

Example 8 was prepared and evaluated in a similar way as discussed abovefor example 5-7, the composition and results given below in table D(amounts in grams). It can be seen that the additional presence of1,2,4-triazole (when compared to example 6) leads to a significantimprovement in pot-life, other advantages being retained.

TABLE D Code Ex8 Sartomer SR355 38.19 Disperbyk 163 2.39 Kronos 231080.12 Malonate polyester A 67.69 Sartomer SR 355 1.15 EtAcAc 0.00 Byk310/315 [1:4 by mass] 0.60 1,2,4-triazole 0.96 Succinimide (s) 0.79 BuAc2.52 MEK 7.20 catalyst solution C2 9.34 recorder drying time (min) 16Potlife (min) 70 Persoz hardness (sec) after 24 h (50 147 mu dry film)

Example formulations 9 and 10, and No-D example formulations 4 and 5were formulated and evaluated along similar lines, now also includingWavescan analysis to have a quantitative indication of the quality ofthe appearance. Compositions and results are given in Table E (amountsin grams).

TABLE E Code Ex9 Ex10 No-D4 No-D5 Sartomer 19.07 19.07 19.07 19.07Disperbyk 163 1.19 1.19 1.19 1.19 Kronos 2310 40.01 40.01 40.01 40.01Malonate polyester A 29.35 33.85 29.35 33.85 Sartomer SR 355 2.11 0.582.11 0.58 EtAcAc 2.41 — 2.41 — Byk 310/315 [1:4 by mass] 0.30 0.30 0.300.30 Succinimide 0.40 0.40 — — BuAc 1.26 1.26 1.26 1.26 MEK 3.60 3.603.60 3.60 Catalyst solution C2 4.67 4.67 4.67 4.67 Persoz hardness (s)at 50 μ 122 125 97 93 Layer thickness (μ) 51 56 58 58 du (dullness) 6.306.40 8.80 11.30 Longwave 3.80 1.90 5.30 7.80 Shortwave 2.20 6.40 18.2024.10 DOI (Dorigon) 94.10 93.90 91.50 88.40 Layer thickness (μ) 92 93 9286 du (dullness) 5.90 8.70 11.60 23.40 Longwave 1.00 3.70 11.50 25.10Shortwave 9.50 24.90 29.70 60.60 DOI (Dorigon) 94.10 90.20 88.10 74.90

Example formulation 9 can be compared with No-D formulation example 4,example formulation 10 can be compared with No-D formulation example 5,difference being the presence of low amounts of succinimide. It can fromboth comparisons be concluded that the presence of succinimide, besidesthe improved Persoz hardness, leads to significantly improved values forlongwave and shortwave roughness, dullness and DOI.

Example 11 Impact on Conversion Kinetics

The conversion of the acryloyls in the system can be followed by FTIR,focusing on the 809 cm⁻¹ band characteristic of the acryloyl. Doingthat, the impact of added succinimide on total conversion can be madevisible. Two systems were formulated (according to compositions of No-Dexample 1 (without succinimide) and example formulation 1 (with 150%succinimide relative to solids). FIG. 1 compares the conversion of thesesystems after application on top of an ATR crystal, the IR beam probingthe deepest layers, close to the substrate. Initial conversion of theformulation without the succinimide is fast, which is also the cause forsolvent entrapment and potential appearance problems. It can be seenthat the addition of succinimide, even at these very low levels, leadsto a significant retardation of the initial conversion; simultaneously,it illustrates that after this initial retardation period, theconversion rate is accelerating, so that the rate of cure towards higherconversions is still fast after this initial delay.

Example 12 Determination of Michael Addition Reactivity of Succinimide

5 grams of succinimide (50.5 mmole) were dissolved in a mixture of 42grams of butyl acrylate and 42 grams of methanol, and maintained at roomtemperature as such, or after adding a strong base (9.82 grams of a 1.12meq/g solution of tetrabutylammonium hydroxide in methanol, 11 meq).Subsequently, the concentration of succinimide is determined as afunction of time by taking samples, neutralizing with a known excess ofHCl in water, and backtitration with a KOH solution. Without baseinitiation, no significant loss of succinimide N—H in this solution isobserved in two weeks. With the base added, the succinimideconcentration can be seen to decrease with time, as illustrated in thetable F below. Succinimide concentration is expressed as % relative tothe theoretical level based on used amounts.

TABLE F Time (min) Succinimide remaining (%) 3 99 30 87 60 77 120 60 18048

At this catalyst level ([succinimide]/[base]=5), it takes about an hourto lose 25% of the succinimide acidic protons to be consumed. Underthese conditions, dimethylmalonate (instead of succinimide) would reactmuch faster with the acrylate.

Further modifications in addition to those described above may be madeto the structures and techniques described herein without departing fromthe spirit and scope of the invention. Accordingly, although specificembodiments have been described, these are examples only and are notlimiting upon the scope of the invention.

What is claimed is: 1) An RMA crosslinkable composition comprising atleast one crosslinkable component comprising reactive components A and Beach comprising at least 2 reactive groups, wherein the at least 2reactive groups of component A are C—H acidic protons in activatedmethylene or methine groups, and the at least 2 reactive groups ofcomponent B are C═C activated unsaturated groups and a base catalyst C,which reactive components A and B crosslink by Real Michael Additionreaction under action of the base catalyst, wherein the at least onecrosslinkable component comprising reactive components A and B in thecomposition has a total hydroxy number of less than 60 mg KOH/g solids.2) The RMA crosslinkable composition according to claim 1, wherein theat least one crosslinkable component comprising reactive components Aand B in the composition has a total hydroxy number less than 20 mgKOH/g solids. 3) The RMA crosslinkable composition according to claim 1,wherein the catalyst C is a carbonate salt according to formula X⁺ROCO₂⁻, wherein X⁺ is a non-acidic cation, and R is hydrogen or a substitutedor unsubstituted alkyl, aryl, or aralkyl group. 4) The RMA crosslinkablecomposition according to claim 1, wherein X⁺ is quaternary ammonium orphosphonium. 5) The RMA crosslinkable composition according to claim 1,wherein the crosslinkable component comprising reactive component A is apolymer comprising an average of 2 to 20 active C—H functions permolecule. 6) The RMA cross-linking composition according to claim 1,wherein more than 50% of the reactive components A in the crosslinkablecomponent are malonate groups. 7) The RMA crosslinkable compositionaccording to claim 1, wherein the component B comprises an unsaturatedacryloyl or maleate functional group. 8) The RMA crosslinkablecomposition according to claim 1, comprising: a. between 5 and 95 wt %of a crosslinkable component comprising component A with at least 2acidic protons C—H in activated methylene or methine, and b. between 5and 95 wt % of a crosslinkable component comprising component B with atleast 2 activated unsaturated groups, wt % relative to the total weightof the crosslinkable composition and c. a catalyst system C thatcontains, or is able to generate a basic catalyst capable of activatingthe RMA reaction between components A and B, wherein the sum of theabove-mentioned components is 100 weight percent and wherein the atleast one crosslinkable component comprising reactive components A and Bin the composition has a total hydroxy number of less than 60 mg KOH/gsolids. 9) The RMA crosslinkable composition according to claim 8,wherein the catalyst system C contains or is able to generate a basiccatalyst capable of activating the RMA reaction between components A andB, at levels of 0.0001 and 0.5 meq/g solid components. 10) The RMAcrosslinkable composition according to claim 8, further comprising anX—H group containing component D that is also a Michael addition donorreactable with component B under the action of catalyst C, wherein X isC, N, P, O or S. 11) The RMA crosslinkable composition according toclaim 8, wherein component D is present in quantities of at least 50mole % relative to base generated by component C, and less than 30 mole% of C—H active groups from component A. 12) The RMA crosslinkablecomposition according to claim 8, further comprising between 0.1 and 80wt % of an organic solvent, which contains at least lwt % of a primaryalcohol and at least 0.1-10 wt % water. 13) The RMA crosslinkablecomposition according to claim 8, wherein the at least one crosslinkablecomponent comprising reactive components A and B in the composition hasa total hydroxy number less than 20 mg KOH/g solids. 14) A kit of partsfor the manufacture of the crosslinkable composition according to claim1, comprising a part 1 comprising the cross-linkable componentscomprising reactive components A and/or B but no C, and part 2comprising component C. 15) A polymeric or oligomeric resin A, for usein a RMA crosslinkable composition according to claim 1, comprising oneor more reactive components A having a structure according to formula 1:

wherein R is hydrogen or an alkyl, aralkyl or aryl substituent and Y andY′ are same or different alkyl, aralkyl or aryl (R*), alkoxy (—OR*)groups or a polymer backbone or wherein the —C(═O)—Y and/or —C(═O)—Y′ isreplaced by CN or phenyl and which polymeric or oligomeric resin A has ahydroxy number of less than 60 mg KOH/g solids, wherein the polymeric oroligomeric resin is a polyester, polyether, polyepoxy, polyurethane orpolycarbonate, comprising reactive component A. 16) The resin Aaccording to claim 15, wherein more than 50% of the reactive componentsA in the crosslinkable component are malonate groups. 17) The resin Aaccording to claim 15, having a number molecular weight between100-20000 gr/mol, and an equivalent weight per reactive component A of100-2000 gr/mol, and an acid number less than 4 mg KOH/gr. 18) Apolymeric or oligomeric resin B for use in a RMA cross-linkablecomposition according to claim 1 comprising one or more reactivecomponents B comprising C═C activated unsaturated groups, and whichpolymeric or oligomeric resin has a hydroxy number of less than 60 mgKOH/g solids, wherein the polymeric or oligomeric resin B is apolyester, polyether, polyepoxy, polyurethane or polycarbonatecomprising reactive component B. 19) The resin B according to claim 18,having a number molecular weight between 300 and 20000 gr/mol, having aequivalent weight per reactive component A or B of 100-2000 gr/mol, anacid number less than 4 mg KOH/gr. 20) Method for preparation of an RMAcrosslinkable composition comprising at least one crosslinkablecomponent comprising reactive components A and B each comprising atleast 2 reactive groups, wherein the at least 2 reactive groups ofcomponent A are C—H acidic protons in activated methylene or methinegroups, and the at least 2 reactive groups of component B are C═Cactivated unsaturated groups and a base catalyst C, which reactivecomponents A and B crosslink by Real Michael Addition reaction underaction of the base catalyst, wherein the at least one crosslinkablecomponent is a resin A, which resin A is a polymeric or oligomeric resincomprising one or more reactive components A having a structureaccording to formula 1:

wherein R is hydrogen or an alkyl, aralkyl or aryl substituent and Y andY′ are same or different alkyl, aralkyl or aryl (R*), alkoxy (—OR*)groups or a polymer backbone or wherein the —C(═O)—Y and/or —C(═O)—Y′ isreplaced by CN or phenyl and which polymeric or oligomeric resin A has ahydroxy number of less than 60 mg KOH/g solids, wherein the polymeric oroligomeric resin is a polyester, polyether, polyepoxy, polyurethane orpolycarbonate; or wherein the at least one crosslinkable component is aresin B, which resin B is a polymeric or oligomeric resin comprising oneor more reactive components B comprising C═C activated unsaturatedgroups, and which polymeric or oligomeric resin has a hydroxy number ofless than 60 mg KOH/g solids, wherein the polymeric or oligomeric resinB is a polyester, polyether, polyepoxy, polyurethane or polycarbonate,or wherein the at least one crosslinkable component is a mixture ofresin A and resin B. 21) Method for the manufacture of coatingcompositions, films or inks comprising: providing the crosslinkingcomposition according to claim
 1. 22) Coating composition comprising theRMA crosslinkable composition according to claim 1, and furthercomprising one or more coating additives such as pigments, co-binders,or solvents.